schirrmacher / rop

Return Oriented Programming Playground

ROP Playground

This Project helps to understand Return Oriented Programming (ROP). I've implemented a vulnerable server, written in C, and a client, written in JavaScript. The client can be used to send malicious messages to the server.

Let's start!

1. Run make debug or make run to start the server
2. Execute the attack with make attack

Note: If you use make run make sure to change the ROP gadget addresses in the client script. This has to be done because Address Space Layout Randomization (ASLR) randomly shifts your ROP gadgets. When you use a debugger ASLR is automatically turned off.

Explanation

When the server starts, it listens on port 1337 for messages with the following byte format:

0    1    2    3         n
+----+----+----+-- ... --+
| ps |  payload          |
+----+----+----+-- ... --+

ps represents the payload size of the message which is sent by the client. Unfortunately, the server doesn't validate incoming ps values. Besides, the buffer which stores the message payload can only hold up to 32 bytes.

When the attacker chooses a value of ps which is greater than 32, a buffer overflow occurs.

1. Classic Buffer Overflow

2. Stack Canaries

3. ASLR